1. Field of the Invention
The present invention relates to an industrial robot system and a control method thereof for performing cooperated work by having the same work space simultaneously shared by an industrial robot and a person.
2. Description of the Related Art
At a production site using a generally-available industrial robot, a safety fence separates a work space of a robot and a work space of a person from each other. Therefore, it is possible to avoid an accident in which a person comes into contact with the robot.
However, there is a production site in which a work space of a robot and a work space of a person cannot be separated from each other, and there is a production site where the productivity is significantly reduced when a work space of a robot and a work space of a person are separated from each other. In such a production site, a robot system that does not require any safety fence is desired.
When no safety fence is used, this increases the risk of a person coming in contact with a robot. Therefore, the impact of a collision of the robot with a person is reduced by, for example, limiting the power of the robot. Alternatively, the robot may be stopped when a person and the robot come into contact with each other.
An example of a work according to a robot system that does not use any safety fence as described above is as follows. In a work space as shown in the following example, a person and a robot conduct a cooperative work with each other.
(1) The robot carries an item from a warehouse to a work space.
(2) In the work space, the robot gives the item to a person.
(3) The robot moves to the warehouse in order to carry an item.
In a conventional robot system, it was necessary to operate an external input of a robot control apparatus with a switch and the like when proceeding from step (2) to step (3). However, in recent years, a person instructs an operation command to a robot by applying an external force to the robot main body.
Japanese Laid-Open Patent Publication No. 2008-200764 also indicates that an operation command is given to a manipulator by applying an external force to the manipulator. More specifically, in Japanese Laid-Open Patent Publication No. 2008-200764, when an operator adds a force to the manipulator with a particular regular pattern, this is recognized with a sensor of the manipulator. Then, a control unit of the manipulator outputs, to the manipulator, an operation command that is determined in accordance with the particular regular pattern.